5-Carbamoyl imidazoles

ABSTRACT

There are provided compounds of the formula: ##STR1## wherein R is an adamantyl group, or a phenyl group unsubstituted or substituted with a lower alkyl group, a lower alkoxy group, a lower alkylthio group, a halogen atom, a nitro group, a cyano group, a methylenedioxy group or an acetamido group, useful as anti-transplanted-tumor agents and immunosuppressants.

This is a continuation-in-part of our application Ser. No. 30,645, filedApr. 16, 1979, now abandoned, which is a continuation of our applicationSer. No. 923,404, filed July 10, 1978, now abandoned, which is acontinuation-in-part of our application Ser. No. 811,597, filed June 30,1977, now abandoned.

The present invention relates to novel imidazole derivatives andpreparation thereof. More particularly, the present invention pertainsto imidazole derivatives useful as antitumor agents andimmunosuppressants, and to their preparation and use.

So far, it has been known that bredinin,4-carbamoyl-1-β-D-ribofuranosylimidazolium-5-olate, hasimmunosuppressive activity and weak antitumor activity against lymphaticleukemia L1210. [Kimio Mizuno et al. J. of Antibiotics, 27, 775 (1974)]

The aglycone of bredinin, 4-carbamoylimidazolium-5-olate, was alsoknown. [Edgar Shipper et al. J. Amer. Chem. Soc., 74, 350 (1952)]However, the pharmacological properties of4-carbomoylimidazolium-5-olate were not known till quite recently.

It is reported that growth inhibitory effects on L5178Y cells andimmunosuppressive effects are produced by administration of4-carbamoylimidazolium-5-olate. It is suggested, however, that theseeffects are not directly produced by it, but they are due to metabolicconversion of 4-carbamoylimidazolium-5-olate to bredinin [KenzoSakaguchi et al. J. of Antibiotics, 28, 798 (1975); T. Tsujino et al.Proceedings of the first intersectional congress of IAMS Vol. 3, 441(1974)]

Imidazole derivatives provided by the present invention arerepresentable by the formula: ##STR2## wherein R is an adamantyl group,or a phenyl group unsubstituted or substituted with a lower alkyl group,a lower alkoxy group, a lower alkylthio group, a halogen atom, a nitrogroup, a cyano group, a methylenedioxy group or an acetamido group.

As used herein, the term "lower alkyl" may preferably include a straightor branched alkyl having 1 to 5 carbon atoms (e.g. methyl, ethyl,n-propyl, isopropyl). The term "lower alkoxy" may preferably include astraight or branched alkoxy having 1 to 5 carbon atoms (e.g. methoxy,ethoxy, n-propoxy, n-butoxy, isobutoxy). The term "lower alkylthio" maypreferably include a straight or branched alkylthio having 1 to 5 carbonatoms (e.g. methylthio, ethylthio). The term "halogen" may preferablyinclude fluorine, chlorine, bromine and iodine.

According to the present invention, the imidazole derivatives of theformula: ##STR3## wherein R is as defined above, can be prepared byreacting 4-carbamoylimidazolium-5-olate of the formula: ##STR4## or itssilylated derivative with reactive derivatives of carboxylic acids ofthe formula:

    RCOOH                                                      (III)

wherein R is as defined above.

Examples of preferred reactive derivatives of carboxylic acids of theformula (III) are carboxylic acid anhydrides and halides, preferablychlorides.

The reaction can generally be effected by cooling a reaction mixture ata temperature from 0° to 100° C., preferably for 0° to 60° C. Thereaction of 4-carbamoxylimidazolium-5-olate with carboxylic acid halidescan usually be carried out in an inert polar solvent or a mixture ofwater and inert organic solvent preferably in the presence of aninorganic or tertiary organic base. Typical examples of said inert polarsolvents are pyridine, dimethylformamide, formamide, dimethylsulfoxide,and dimethylacetamide. Typical examples of said inert organic solventsare ethyl ether, benzene, toluene, chloroform, ethylacetate, n-hexane,and xylene. Examples of preferred inorganic base are sodium hydroxide,sodium carbonate, sodium bicarbonate, potassium carbonate or bicarbonateand potassium hydroxide. Examples of preferred tertiary organic base aretriethylamine, N,N-dimethylaniline, and pyridine.

The reaction of 4-carbamoylimidazolium-5-olate with carboxylic acidanhydrides can be carried out in the presence of an inert organicsolvent (e.g. methanol, ethanol, dimethylformamide, dimethylsulfoxide,formamide, dimethylacetamide, acetnitrile, acetone, nitromethane, ethylacetate).

The compounds of the formula (I) can also be prepared by reactingsilylated derivative of 4-carbmoylimidazolium-5-olate with aforesaidcarboxylic acid halides in an inert organic solvent (e.g. benzene,toluene, xylene, ethylacetate, n-hexane, dichloroethane, anhydrous ethylether, anhydrous dioxane, anhydrous tetrahydrofuran).

The reaction can be effected by cooling at a temperature -10° to 30° C.,preferably for 1 to 10 hours.

The silylated derivative of 4-carbamoylimidazolium-5-olate are known andcan be prepared by known methods. [Hayashi et al. Japanese Patent Kokai50-121276]4-carbamoylimidazolium-5-olate may exist in the form of thetautomers as follows, ##STR5## so the position of acylation may beambiguous.

The compounds of the present invention were incorrectly identified bythe formula, ##STR6## wherein R is as defined above, in our previousapplication Ser. No. 923,404 though they were correctly identified bythe formula: ##STR7## wherein R is as defined above, in our firstapplication Ser. No. 811,597.

Although, in the previous description, the structure of the imidazolederivatives of the present invention is given as represented by theformula (I). The imidazole derivatives of the present invention mayexist in a mixture of the two tautomers as follows: ##STR8## both ofwhich are within the scope of the present invention.

The compounds of the formula (I) possess excellent immunosuppressiveactivity as well as potent anti-transplanted tumor activity.

For example, they exhibit much higher immunosuppressive activity thanthose of 6-(1-methyl-4-nitro-5-imidazolyl)mercaptopurine (Azathioprine)and 6-mercaptopurine.

The immunosuppressive activities of the compounds of the presentinvention, Azathioprine and 6-mercaptopurine are given in the followingtable. After a sheep red blood cell preparation (SRBC) was injected inmice, the compounds were administered orally once a day on days 0 to 3.The plaque forming cell (PFC) number was measured on day 4 by Cunninghammethod. [Cunningham A. J. et al. Immunol. 14, 599 (1968)]

                  TABLE I                                                         ______________________________________                                                   Dose                    Suppre-                                               mg/kg/day Effects       ssion                                      Compounds  p.o       PFC/spleen × 10.sup.-4                                                                (%)                                        ______________________________________                                        5-Carbamoyl-1H-                                                                          25        19.88 ± 6.06.sup.a                                                                       68.1                                       imidazole-4-yl                                                                benzoate   100        8.63 ± 2.61.sup.b                                                                       89.4                                       5-Carbamoyl-1H-                                                                          25        14.19 ± 2.24.sup.a                                                                       77.2                                       imidazole-4-yl                                                                1-adamantane                                                                  carboxylate                                                                              100        5.19 ± 1.29.sup.b                                                                       93.6                                       5-Carbamoyl-1H-                                                               imidazole-4-yl                                                                           25        22.06 ± 5.37.sup.a                                                                       64.6                                       p-chlorobenzoate                                                              6-Mercaptopurine                                                                         25        30.78 ± 6.28                                                                             60.2                                       Azathioprine                                                                             100       26.73         81.6                                       Control.sup.a        62.25 ± 11.73                                         Control.sup.b        81.44 ± 6.56                                          ______________________________________                                    

The compounds of the present invention have also been found to possesspotent antitumor activities against Sarcoma 180, Ehrlich carcinoma,hepatoma MH 134, and P388 leukemia. They exhibit particularly excellentinhibitory effects against solid transplanted tumors.

The antitumor activities of the compounds of the present invention wereestimated according to the methods described in "Oyo-Yakuri," Vol. 14,P. 521 (in Japanese).

The results are given in the following Tables II and III.

                  TABLE II                                                        ______________________________________                                        Antitumor effect on mouse                                                     experimental tumors                                                                          Dosage mg/kg,                                                                             Inhibition Ratio (%)                               Compound       Route i.p.  Sarcoma 180 (solid)                                ______________________________________                                        5-Carbamoyl-1H-                                                                              50          53.9                                               imidazol-4-yl  100         71.4                                               1-adamantane-  200         88.8                                               carboxylate    206         100.0                                              5-Carbamoyl-1H-                                                               imidazol-4-yl                                                                 p-chlorobenzoate                                                                             100         49.1                                               5-Carbamoyl-1H-                                                               imidazol-4-yl                                                                 p-fluorobenzoate                                                                             100         36.0                                               5-Carbamoyl-1H-                                                               imidazol-4-yl                                                                 p-nitrobenzoate                                                                              100         44.7                                               5-Carbamoyl-1H-imidazol-                                                      4-yl 3,4-methylenedioxy-                                                      benzoate       100         65.1                                               5-Carbamoyl-1H-imidazol-                                                      4-yl m-cyanobenzoate                                                                         100         38.3                                               5-Carbamoyl-1H-imidazol-                                                      4-yl p-methylbenzoate                                                                        100         38.3                                               5-Carbamoyl-1H-imidazol-                                                      4-yl p-bromobenzoate                                                                         100         66                                                 Mitomycin C    2           74.0                                               5-Fluorouracil 30          66.0                                               ______________________________________                                    

ICR-JCL male mice, 5 weeks old, weighing between 23 and 26 grams wereused. Each test group was composed of 5 mice. One million cells ofSarcoma 180 were injected intramusculary in hind leg. The drug wasadministered intrapenitoneally at day 1, 3, 5, 7 and 9. After killingthe mice at day 10, tumors were removed and weighed. The tumorinhibitory ratio was calculated according to the following formula.##EQU1##

                  TABLE III                                                       ______________________________________                                        Antitumor effect on mouse                                                     experimental tumor                                                                                Dosage   Evaluation                                       Compound            mg/kg    T/C (%) P388                                     ______________________________________                                        5-Carbamoyl-1H-imidazole-                                                                         400      138                                              4-yl 1-adamantanecarboxylate                                                                      200      120                                                                  100      112                                              ______________________________________                                         animals: CDF.sub.1 mouse (6 mice/group)                                       tumor: mouse leukemia P388                                                    inoculum size: 10.sup.6 cells/mouse                                           inoculum site: i.p.                                                           day of administration: day 1 & 5                                              administration route: i.p.                                                    dose: 100, 200 & 400 mg/kg                                                    evaluation: median survival time                                         

The compounds (I) of the present invention have low toxicity. They donot show any toxic symptoms, when over 1000 mg/kg of the compounds areorally administered to a mouse. Moreover, they do not exhibit aninfluence on decrease of peripheral leucocytes, which is one of the mostserious side effects of immunosuppressants.

For the oral or parenteral administration, they are made up alone ortogether with a conventional pharmaceutical carrier or diluent to aconventional solid or liquid pharmaceutical preparation (e.g. powders,granules, tablets, capsules, suspensions, emulsions, solutions) usingthe conventional methods in pharmaceutical field.

The following examples are given to illustrate the present inventionmore precisely but it is not intended to limit the present inventionthereto.

EXAMPLE 1

To a suspension of 455 mg of 4-carbamoylimidazolium-5-olate in 5 ml ofdry pyridine was added 1.02 g of benzoyl chloride at a temperature below5° C. After addition was over, the mixture was stirred under ice coolingfor 2 hours. Then separated crystals were filtered off, washed withwater and ether, dried to give 5-carbamoyl-1H-imidazol-4-yl benzoate,m.p. 204° C. (dec.).

ν_(max) ^(nujol) (cm⁻¹ ; 3450, 3170, 3100 (NH), 1740 ##STR9##

EXAMPLE 2

To a suspension of 508 mg of 4-carbamoylimidazolium-5-olate and 486 mgof triethylamine in 6 ml of anhydrous dimethylformamide was added 770 mgof p-chlorobenzoyl chloride in 3 ml of anhydrous dimethylformamide at atemperature below 5° C. The mixture was stirred under ice cooling for 4hours. The insoluble crystals were filtered off, then the filtrate wereconcentrated to a residue under reduced pressure, and the resultingresidue was dissolved in chloroform. The chloroform solution was washedwith water, and dried over anhydrous sodium sulfate. The solvent wasremoved under reduced pressure to give 5-carbamoyl-1H-imidazol-4-ylp-chlorobenzoate. The crude solid was washed with ethyl acetate to give340 mg of pure product, m.p. 220° C. (charred).

The following compounds were obtained by substantially the sameprocedures as described above:

5-Carbamoyl-1H-imidazol-4-yl p-nitrobenzoate

m.p. 177°-184° C. (dec.)

5-Carbamoyl-1H-imidazol-4-yl p-fluorobenzoate

m.p. 214° C. (dec.)

EXAMPLE 3

A mixture of hexamethyldisilazane (10 g), a catalytic amount of ammoniumsulfate and 4-carbamoylimidazolium-5-olate (745 mg) was refluxed for anhour and a half. The solution was condensed under reduced pressure togive sililated 4-carbamoylimidazolium-5-olate derivative. The resultingsolid (345 mg) was dissolved in dry benzene (30 ml). To the benzenesolution was added 350 mg of p-chlorobenzylchloride under ice cooling,then the mixture was stirred for 3 hours and for 6 hours at roomtemperature. The resulting solution was evaporated in vacuo to drynessand the resulting solid was washed with ethyl acetate to give5-carbamoyl-1H-imidazol-4-yl p-chlorobenzoate, m.p. 220° C. (charred).

EXAMPLE 4

To a mixture of 1.27 g of 4-carbamoylimidazolium-5-olate in 42.4 g of10% aqueous solution of sodium carbonate was added 7.38 g of3,4-methylenedioxybenzoylchloride in 20 ml of toluene at roomtemperature. After addition was over, the mixture was stirred for 4hours. Then the separated crystals were filtered off, washed with waterand toluene, dried in vacuo to give 5-carbamoyl-1H-imidazol-4-yl3,4-methylenedioxybenzoate, m.p. 206.5°-208° C. (dec.).

And the following compounds were obtained by the manner similar to thatdescribed in Example 4.

5-Carbamoyl-1H-imidazol-4-yl o-methoxybenzoate

m.p. 205° C. (charred).

5-Carbamoyl-1H-imidazol-4-yl m-cyanobenzoate

m.p. 195° C. (dec.).

5-Carbamoyl-1H-imidazol-4-yl p-methylbenzoate

m.p. 211° C. (dec.).

EXAMPLE 5

To a solution of 1-adamantanecarbonylchloride (39.73 g) in pyridine (260ml) was added 4-carbamoylimidazolium-5-olate (12.71 g) and the reactiontemperature was maintained at 41°-43° C. for 3.5 hours. Pyridine wasremoved under reduced pressure. To the residue was added ethylacetate(300 ml) and water (300 ml), and stirred at room temperature for 1 hour.The insoluble solid was filtered and washed with ethyl acetate to givealmost pure 5-carbamoyl-1H-imidazol-4-yl 1-adamantanecarboxylate (25.9g, β form, m.p. 205°-205.5° C. (dec.)). Recrystallization fromdimethylformamide-diethylether gave analytically pure sample (β formm.p. 213.5°-216.5° C. (dec.)).

Elemental analysis:

Calculated for C₁₅ H₁₉ O₃ N₃ =289.³³

    ______________________________________                                                  C; 62.26%,  H; 6.62%,   N; 14.52%                                   Found     C; 62.5%,   H; 6.7%,    N; 14.7%                                    ______________________________________                                    

EXAMPLE 6

To a suspension of 4-carbamoylimidazolium-5-olate (1.016 g) indimethylformamide (20 ml) was added triethylamine (1.942 g) at 0°-5° C.and then 1-adamantanecarbonylchloride (3.50 g) in dimethylformamide (20ml) dropwisely over 24 minutes. The reaction mixture was stirred at0°-5° C. for 23 hours. The solvent was removed under reduced pressure.To the residue was added ethyl acetate (20 ml) and water (20 ml), andstirred at room temperature for 1 hour. The insoluble solid was filteredand washed with ethyl acetate to give almost pure5-carbamoyl-1H-imidazol-4-yl 1-adamantanecarboxylate (1.5 g, α form,m.p. 206.5°-207.5° C. (dec.)), which was washed thoroughly with ethylacetate to give pure product, α form, m.p. 211° C. (dec.).

EXAMPLE 7

To a solution of 1-adamantanecarbonylchloride (2.980 g) in pyridine (26ml) was added 4-carbamoylimidazolium-5-olate (1.271 g) and the reactiontemperature was kept at 40°-43° C. for 4 hours. Unreacted startingmaterial was recovered by filtration (210 mg). The filtrate wasconcentrated under reduced pressure. To the residue was added ethylacetate (30 ml) and water (30 ml), and stirred at room temperature for 1hour. The insoluble solid was filtered and washed with ethyl acetate togive almost pure 5-carbamoyl-1H-imidazol-4-yl 1-adamantanecarboxylate(1.602 g, α form, m.p. 207°-209° C. (dec.)).

EXAMPLE 8

To a suspension of 4-carbamoylimidazolium-5-olate (1.271 g) in pyridine(16 ml) was added dropwisely 1-adamantanecarbonylchloride (4.371 g) indimethylformamide (28 ml) over 17 minutes. The reaction mixture wasstirred at 65°-67° C. for 6 hours and then concentrated under reducedpressure. To the residue was added ethyl acetate (30 ml) and water (30ml), and stirred at room temperature for 1 hour. The insoluble solid wasfiltered and washed with ethyl acetate to give5-carbomoyl-1H-imidazol-4-yl 1-adamantanecarboxylate (1.372 g, α form,m.p. 207°-208° C. (dec.)). Additional product (0.335 g, β form, m.p.205°-208° C. (dec.)) was obtained from the organic layer of the filtrateafter the operation mentioned above.

EXAMPLE 9

To a suspension of 4-carbamoylimidazolium-5-olate (4.064 g) indimethylformamide (80 ml) was added triethylamine (7.768 g) at 0°-5° C.and then 1-adamantanecarbonylchloride (14.00 g) in dimethylformamide (80ml) dropwisely over 22 minutes. The reaction mixture was stirred at0°-5° C. for 15 hours. The solvent was removed under reduced pressure.To the residue was added ethyl acetate (100 ml) and water (100 ml), andstirred at room temperature for 1 hours. The insoluble solid wasfiltered and washed with ethyl acetate to give almost pure5-carbamoyl-1H-imidazol-4-yl 1-adamantanecarboxylate (5.67 g, β form,m.p. 207°-210° C. (dec.)).

EXAMPLE 10

To a suspension of 5.084 g of 4-carbamoyl-imidazolium-5-olate in 104 mlof dry pyridine was added 11.41 g of p-bromobenzoyl chloride at roomtemperature. After addition was over, the mixture was stirred at 40°-45°C. for 2.5 hours. The separated crystals were filtered off, washed withchloroform and diisopropyl ether, dried under vacuum to give 10.535 g of5-carbamoyl-1H-imidazol-4-yl p-bromobenzoate, m.p. 232°-233° C. (dec.)

Elemental analysis:

Calculated for C₁₁ H₈ N₃ O₃ Br (310.10):

    ______________________________________                                                C       H         N         Br                                        ______________________________________                                                  42.60%    2.60%     13.55%  25.77%                                  Found:    42.6%     2.5%      13.8%   25.76%                                  ______________________________________                                    

EXAMPLE 11

To a suspension of 636 mg of 4-carbamoylimidazolium-5-olate in 15 ml ofdry pyridine was dropwisely added 1.0 g of o-methylbenzoyl chloride atless than 5° C. in N₂ atmosphere. After being stirred for 2 hours at41°-43° C., the reaction mixture was cooled to room temperature and 658mg of triethylamine was added. Then the reaction mixture wasconcentrated under reduced pressure. To the residue was added chloroform(about 20 ml) and then separated crystals were filtered off, washed withchloroform, toluene and ether, and dried to give 600 mg of5-carbamoyl-1H-imidazol-4-yl o-methyl benzoate, m.p. 181.5°-182.5° C.

Recrystallized was 447 mg of crude material from N,N-dimethylformamideand water.

Amount: 416 mg.

m.p.: 185°-185.5° C. (dec.)

ν_(max) ^(nujol) (cm⁻¹): 3460, 3170, 1740, 1675, 1610, 1470, 1435, 1255,735.

Elemental analysis:

Calculated for C₁₂ H₁₁ O₃ N₃.O.3H₂ O

    ______________________________________                                                  C        H          N                                               ______________________________________                                                    57.50%     4.66%      16.76%                                      Found:      57.48%     4.34%      16.91%                                      ______________________________________                                    

The following compound was obtained in the same manner as describedabove.

1.258 g of 5-carbamoyl-1H-imidazol-4-yl p-methylthiobenzoate wassynthesized from 0.636 g of 4-carbamoylimidazolium-5 olate and 1.4 g ofp-methylthiobenzoyl chloride.

m.p. 219° C. (charred)

Recrystallized was 512 mg of crude material from N,N-dimethylformamideand water.

Amount: 495 mg.

m.p.: 219° C. (charred)

ν_(max) ^(nujol) (cm⁻¹): 3440, 1725, 1665, 1600, 1590, 1460, 1370, 1270.

Elemental analysis:

Calculated for C₁₂ H₁₁ N₃ O₃ S:

    ______________________________________                                                  C        H          N                                               ______________________________________                                                    51.98%     4.00%      15.15%                                      Found:      52.0%      3.7%       15.0%                                       ______________________________________                                    

0.255 g of 5-carbamoyl-1H-imidazol-4-yl o-chlorobenzoate was synthesizedfrom 0.524 g of 4-carbamoylimidazolium-5 olate and 0.952 g ofo-chlorobenzoyl chloride,

m.p. 144.5°-147.5° C. (dec.)

ν_(max) ^(nujol) (cm⁻¹): 3460, 3420, 3150, 1750, 1660, 1590, 1450, 1370,1230, 1010, 730

Elemental analysis:

Calculated for C₁₁ H₈ N₃ O₃ Cl.1H₂ O:

    ______________________________________                                                C       H         N         Cl                                        ______________________________________                                                  46.58%    3.55%     14.8%   12.50%                                  Found:    46.7%     3.6%      15.3%   12.83%                                  ______________________________________                                    

According to the present invention, there are obtained, for example, thefollowing compounds:

5-Carbamoyl-1H-imidazol-4-yl m-chlorobenzoate,

5-Carbomoyl-1H-imidazol-4-yl p-acetamidobenzoate,

5-Carbamoyl-1H-imidazol-4-yl o-fluorobenzoate,

5-Carbamoyl-1H-imidazol-4-yl m-fluorobenzoate,

5-Carbamoyl-1H-imidazol-4-yl m-nitrobenzoate,

5-Carbamoyl-1H-imidazol-4-yl o-nitrobenzoate.

What is claimed is:
 1. A compound of the formula ##STR10## wherein R isan adamantyl group, or a phenyl group unsubstituted or substituted witha lower alkyl group, a lower alkoxy group, a lower alkylthio group, ahalogen atom, a nitro group, a cyano group, a methylenedioxy group or anacetamido group.
 2. A compound according to claim 1, wherein R is aphenyl group substituted with a lower alkyl group, a lower alkoxy group,a lower alkylthio group, a halogen atom, a nitro group, a cyano group, amethylenedioxy group, or an acetamido group.
 3. A compound according toclaim 1, wherein R is adamantyl.
 4. A compound according to claim 1,wherein R is phenyl.
 5. A compound according to claim 2, wherein R isp-chlorophenyl.
 6. A compound according to claim 2, wherein R is3,4-methylenedioxyphenyl.
 7. A compound according to claim 2, wherein Ris p-nitrophenyl.
 8. A compound according to claim 2, wherein R isparafluorophenyl.
 9. A compound according to claim 2, wherein R iso-methoxyphenyl.
 10. A compound according to claim 2, wherein R ism-cyanophenyl.
 11. A compound according to claim 2, wherein R isp-tolyl.
 12. A compound according to claim 2 wherein R is p-bromophenyl.13. A compound according to claim 2, wherein R is o-tolyl.
 14. Acompound according to claim 2, wherein R is p-methylthiophenyl.
 15. Acompound according to claim 2, wherein R is p-chlorophenyl.